and to place your world ingame, you just need to point your server at the modified files (put folder/directory in datapath.cs), and then distribute those files to your players via either patches or simply having nthem overwrite their existing files
for maps, the files would be as follows:
map0.mul (terrain and altitude data)
statics0.mul (statics on top of the actual map, vegetation, buildings etc.)
staidx0.mul (statics index file)
note the zero is the index of the map you are using, so if it were trammel that you are replacing, the filenames would be map1.mul, staidx1.mul statics1.mul etc.
the map has to replace an existing map as of current, but the map can be any size from 8x8 to 7168 x 4096 but both the length and width must be multiples of 8